1. Field of the Invention
The present invention relates to methods and apparatus for restoration of functionality to weapons when they become jammed.
2. Background and Related Art
Most modern firearms employ cartridges that are cycled into and out of a weapon's chamber for firing a projectile at a target. These cartridges are typically made of brass or another metal alloy that resists corrosion and has low friction characteristics. Some cartridges are made from steel, but have a lacquer coating or some other coating to impede corrosion. Steel cartridges are typically vastly inferior to brass, but are produced more economically.
A typical rifle cartridge may be described with reference to FIGS. 1 and 2, which is a side view of a typical rifle cartridge. A typical rifle cartridge 1 comprises a brass or metallic body 2 with a rim 6 at the base of the cartridge and extractor groove 8 for manipulating the cartridge during loading and extraction operations. The shoulder 10 and neck 12 serve to taper a larger cartridge down to the diameter of the bullet or projectile 4. A cartridge is typically hollow and is filled with a specific amount of propellant, otherwise known as gun powder. The projectile 4 is typically placed into the open end of the cartridge neck with a friction fit so that it does not slide out before firing.
FIG. 2 shows an end view of the cartridge shown in FIG. 1 with the outer diameter of the cartridge base defined by the rim 6. This typical cartridge is a centerfire cartridge wherein the center of the cartridge base comprises a hole 20 into which a primer is friction fit. The primer serves to ignite the propellant in the cartridge when the primer is struck by the firing pin of a weapon.
The typical cartridge shown is the most common in military, hunting, target and other sport rifles and has a rebated rim that has an outer diameter typically slightly smaller than the body diameter of cartridge. However, another common cartridge type has a rim that protrudes beyond the diameter of the cartridge with no extractor groove.
A cartridge is typically manipulated into and out of a weapon's firing chamber by the weapon's action. Many types of actions are in use today, but the most common are manual actions, such as the bolt action, lever action and pump action, the semi-automatic action and the automatic or fully-automatic action.
The manual action weapons require manual manipulation of a bolt, lever or sliding forearm “pump” to manually extract and load cartridges from and into the firing chamber. A semi-automatic weapon automatically loads and extracts a cartridge into and out of a weapon once each time the trigger is pulled. The user needs only to pull the trigger each time he/she desires to fire the weapon until the magazine is empty. A fully-automatic weapon's action loads cartridges into and out of the weapon automatically and continuously as long as the trigger remains pulled and the magazine contains cartridges.
When a cartridge is bent, deformed, dirty, corroded or has otherwise lost its standard geometric and/or frictional properties or when the weapon is dirty, corroded, damaged or otherwise impaired, the cartridge may become difficult to load or unload or may even jam somewhere in the action or in the firing chamber. This jamming is common when old, low-quality and/or dirty ammunition is used or when a weapon is dirty, unlubricated and/or damaged.
The AR-10 rifle is a semi-automatic, 7.62×51 mm NATO caliber weapon designed by Armalite Corporation. Several variants and copies have been manufactured and are still manufactured today. It uses a direct impingement gas action with a rotary bolt locking mechanism. The direct impingement gas operation design directs hot exhaust gases from the weapon barrel, through a tube, against a bolt key and then into the bolt carrier. This design allows hot combustion gases to flow over the bolt carrier and action of the weapon. After extended use, these combustion gases will cause a buildup of residue that can cause the action to jam.
The AR-15 is another Armalite-designed weapon that is basically a scaled down version of the AR-10 using the 5.56×45 mm caliber NATO cartridge. It uses the same basic design as the AR-10 and suffers from the same weaknesses in design. The AR-15 was modified for the US military and adopted as the M16 and M4 select-fire, fully-automatic weapons. When put into widespread military use in Vietnam, the M16 suffered from frequent jamming unless cleaned properly and used with ammunition employing clean-burning propellant.
As the design is a military standard, dozens of manufacturers now manufacture AR-15 or AR-15 style weapons. In fact, it is one of the most popular and ubiquitous rifles in the U.S. civilian market today while the M16 is an extremely common military weapon used in dozens of military forces across the world.
Other weapons with the same basic design include the DPMS Panther Arms LR-308, LRAP4 and GII AP4; the Colt MARC 901 rifles; and the Lewis Machine and Tool LM308SS in 7.62×51 mm caliber and many well-known models in 5.56×45 mm caliber from DPMS Panther Arms, Colt, LMT, Rock River Arms, Bushmaster, STAG Arms, Bravo Company USA, CMMG, Daniel Defense, Noveske, Sig Sauer, Smith & Wesson, Ruger and others.
Many automatic and semi-automatic weapons are susceptible to jamming if they are poorly lubricated or dirty as the actions are operated by gas pressure and spring return mechanisms that are specifically tuned for the forces encountered during normal operation. Hence, when friction forces build up, the weapon simply stops functioning because the spring forces are not balance to overcome the increased frictional forces in the action. With a manual action, the user can simply increase the force on the bolt, but with a semi-automatic, the spring force cannot be increased and the weapon jams.
While the AR-10 and AR-15 function well when cleaned and maintained properly and used with high quality ammunition, they can jam frequently when poorly lubricated and/or dirty. Typically, when the weapon jams, the bolt carrier, bolt or cartridge become stuck in the chamber or receiver. When this occurs, the action must be forced open manually.